Nisoldipine Increases the Bioavailability of Endothelial NO

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/11811245 Nisoldipine increases the bioavailability of endothelial NO Article in Naunyn-Schmiedeberg's Archives of Pharmacology · August 2001 DOI: 10.1007/s002100100429 · Source: PubMed CITATIONS READS 8 40 8 authors, including: Renate Rösen University of Cologne 81 PUBLICATIONS 3,244 CITATIONS SEE PROFILE All content following this page was uploaded by Renate Rösen on 14 February 2015. The user has requested enhancement of the downloaded file. Naunyn-Schmiedeberg’s Arch Pharmacol (2001) 364:110–116 DOI 10.1007/s002100100429 ORIGINAL ARTICLE Reinhard Berkels · Renate Roesen · Henning Bartels · Svenja Purol-Schnabel · Isik Kirmiziguel · Hailey Farmer · Gustav V. R. Born · Wolfgang Klaus Nisoldipine increases the bioavailability of endothelial NO Received: 24 November 2000 / Accepted: 20 March 2001 / Published online: 1 June 2001 © Springer-Verlag 2001 Abstract Different observations suggest that dihydropy- Keywords Endothelium · Nisoldipine · Nitric oxide · ridine calcium antagonists alter endothelial NO release. Calcium antagonist · Antioxidative Therefore, in a first step we investigated whether part of the nisoldipine (a dihydropyridine calcium antagonist with a possible selectivity for coronaries)-induced vasore- Introduction laxation was due to an NO release from the endothelium in porcine coronary arteries. Secondly, we directly mea- Dihydropyridine (DHP)-type calcium antagonists are im- sured whether nisoldipine increased NO release from rab- portant drugs in the treatment of hypertension, angina bit aorta or the nisoldipine enantiomers (Bay R 1223, Bay pectoris and coronary heart diseases (Frishman 1994). They R 1224) from rat aorta. Thirdly, we determined whether induce vascular relaxation by binding to smooth muscle nisoldipine exerted antioxidative properties in segments L-type calcium channels thus modulating the vascular of porcine aorta with intact endothelium. tone via inhibition of the calcium influx (Catterall and Blocking endothelial NO synthase with N-nitro-L-argi- Striessnig 1992; Tsien et al. 1987). Findings demonstrate nine resulted in a significant shift of the relaxation curve that a nitrendipine-induced vasodilatation may in part be to higher concentrations. Accordingly, nisoldipine in- dependent on endothelial functions since removal of the duced a concentration-dependent release of NO (direct endothelium or blockade of the guanylate cyclase, the tar- electrochemical detection) from native endothelium get of endothelium-derived NO, resulted in a shift of con- which already started at a therapeutical level (1 nmol/l centration-response curves to higher values (Kojda et al. nisoldipine/6.5±1.2 nmol/l NO). To evaluate whether this 1990, 1991). It has been shown by several groups that the effect was due to an antioxidative protection of NO, we DHPs nifedipine, nitrendipine, amlodipine, felodipine and examined the influence of nisoldipine on a hyperglycemia pranidipine as well as the calcium agonist Bay K 8644 en- (30 mmol/l, 20 min)-induced reactive oxygen species re- hance the release or prolong the biological action of nitric lease of vascular endothelium from porcine coronary ar- oxide (Berkels et al. 1996, 1999a, 1999b; Dhein et al. teries. Nisoldipine concentration-dependently reduced the 1995; Ding and Vaziri 1998; Gunther et al. 1992; Salameh reactive oxygen species release (>50%; 10 µmol/l). More- et al. 1996; Salomone et al. 1996; Verhaar et al. 1999; over, a carbachol-induced NO release (rabbit aorta) which Zhang and Hintze 1998) from the endothelium. Since was significantly diminished by hyperglycemia was com- macrovascular endothelial cells (EC) are lacking voltage- pletely restored in the presence of nisoldipine (3 µmol/l). operated L-type calcium channels (Adams et al. 1989; We conclude that nisoldipine increases the NO bioavail- Colden-Stanfield et al. 1987), DHPs must exert their ef- ability which may result in an ameliorated endothelial fects via other mechanisms. function. However, none of the DHPs investigated have a prevalence for the coronary vasculature. Since the calcium antagonist nisoldipine (NIS) is thought to have a higher R. Berkels (✉) · R. Roesen · H. Bartels · S. Purol-Schnabel · prevalence for coronary arteries (Godfraind et al. 1987, I. Kirmiziguel · W. Klaus 1992; Salomone et al. 1996), we wanted to examine whether Institute of Pharmacology, University of Cologne, NIS modulates endothelial functions, too. Therefore, re- Gleueler Strasse 24, 50931 Cologne, Germany e-mail: [email protected], laxation of porcine coronaries were studied in comparison Tel.: +49-221-4783405, Fax: +49-221-4785022 with coronaries in which the endothelial NOS was inhib- H. Farmer · G.V.R. Born ited. Furthermore, the release of NO from native endothe- The William Harvey Research Institute, lium was directly measured under the influence of NIS St. Bartholomew’s Hospital Medical College, London, UK and its enantiomers as well as the formation of nitrite, the 111 degradation product of NO. Since some DHPs exert an- taken to preserve the endothelium. The arteries were cut into rings tioxidative properties (Janero and Burghardt 1989; Mak of 0.3 cm (wet weight 2–3 g) and the rings opened by a longitudi- nal cut. The pieces were incubated in 450 µl of a HEPES-buffered and Weglicki 1990, 1994; Silva et al. 1998; Weglicki et al. saline solution for 20 min at 37°C. Hyperglycemia (30 mmol/l glu- 1992), we additionally investigated if NIS may inhibit the cose) was used to induce an increase in the ROS formation from hyperglycemia-induced ROS (reactive oxygen species), vascular endothelium (Du et al. 1999; Honing et al. 1998; Tes- i.e. the NO release from porcine coronary arteries. famariam and Cohen 1992). After 20 min lucigenin (0.25 mmol/l; Sigma) was added (final volume 500 µl) and the emitted chemilu- minescence was immediately recorded for 1 min (Berthold Bi- olumat LB 9500). The respective backgrounds were subtracted. Materials and methods The solvent (DMSO, <0.01%) did not interfere with the measurements. Organ bath experiments. Experiments were performed as previ- ously described (Gunther et al. 1992) on right coronary arteries Measurement of NO formation from vascular endothelium. The from 5- to 7-month-old pigs (70–90 kg) obtained from the local thoracic aortas of rabbits (White New Zealand rabbits) and rats slaughterhouse. Briefly, branches of the rapidly dissected hearts, (Wistar rats) were prepared immediately after a concussion with a removed 20–30 min after death, were gently flushed with cold subsequent exsanguination and stored in HEPES buffer. Special care was taken to preserve the endothelium during removal of con- oxygenated (95% O2 + 5% CO2) tyrode solution. After carefully removing all loosely adherent tissue, proximal parts of the arteries nective tissue. The vessels were opened longitudinally by a single were cut into ring segments (3–4 mm) and mounted between stain- cut. A strip of 4 cm length (2 cm for rats) was spread in an organ less steel triangles in a 10-ml jacketed organ bath (37°C). Changes bath and fixed at both ends with the luminal surface of the vessel in arterial diameter were measured using an isotonic transducer turned upward. The electrode was placed in a fixed distance of and recorded after amplification (DMS-DC amplifier; Fleck, 1 mm in front of the endothelium. All substances were applied to Mainz, Germany) with a computer. Preload was adjusted to 2.0 g. the same place in the organ bath. The NO release was monitored The contractile response of the arteries was calculated from the ob- on-line. Data given represent the maximal increase of NO forma- served changes in their diameter. To reach a constant resting ten- tion after application of the substances. Prior to all experiments it sion of the arteries, equilibration was performed for 45–60 min. was tested that the endothelium was functionally intact using stan- The degree of intact endothelial and smooth muscle function dard agonists (substance P, bradykinin, carbachol; Sigma) to elicit was controlled by the addition of 3 nmol/l Substance P (Sigma), an NO release. To work with the highly sensitive electrode, it is a common stimulator of NO synthesis, after precontraction with necessary to ground the experimentator and the recording devices µ thoroughly; otherwise small changes in electric currents will inter- 10 mol/l PGF2α (Sigma). Only vessels with at least 70% relaxation (response to substance P) were included in further experi- fere with the recording. The same applies to changes in pH, flow ments. After a washout period coronaries were finally contracted and temperature. µ NIS and its enantiomers (Bay R 1223, Bay R 1224; Bayer Vi- with 50 mol/l PGF2α, which resulted in a reproducible and maximal contraction. NIS (Bayer Vital) was then added in a cumulative tal) in maximum concentrations (no vessel segments present) did manner. Any preincubations with NNA (50 µmol/l; Sigma) lasted not elicit an NO signal. The DHP were dissolved in 100% DMSO for 45 min. To prevent photodegradation of NIS, all experiments (10 mmol/l) and then diluted in aqueous solutions (0.1 mmol/l). In corresponding experiments it was shown that the solvent DMSO were carried out under sodium light. Drug-induced relaxation of ≤ the artery segments was expressed as percentage of the maximal (final concentration 0.01%) did not affect the measurements ei- ther. response elicited by PGF α. 2 Using the above-described method we could measure on-line the acute NO concentrations elicited by certain agonists, but not Calibration of the NO electrode. The ISO-NO electrode (Tsuka- the total amount (basal and stimulated) of nitric oxide released. hara et al. 1993; WPI, Sarasota, Fla., USA) was calibrated using a This is due to the fact that the constitutively released NO is part of chemical titration method according to the manufacturer (WPI) the baseline which establishes after we put the electrode upon the utilising a solution (0.1 mol/l H SO , 0.14 mol/l K SO , 0.1 mol/l 2 4 2 4 endothelium.

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